Orbit Determination and Analysis of Chang'E-4 Relay Satellite on Mission Orbit

Abstract

Chang'E-4 relay satellite that flying on the mission orbit at the Earth-Moon L2 is the key for the probe to complete the landing and inspection on the farside of the moon,with the mission orbit of the southern clan Halo orbit with an average period of 14 days. Due to mission requirements, the + Z axis of the relay satellite will be in two states:orientation to the sun and orientation to the moon or the earth. In the non-directional orientation of the sun, the solar pressure will accelerate the angular momentum accumulation of satellites and increase the frequency of satellite jets. In this paper,under the existing TT&C conditions, the orbit determination accuracy of satellites in the two states is analyzed and evaluated by using overlapping arc method. The results show that the position error of overlapping arcs is 1.6 km and the velocity error is 8 mm/s for the relay satellite when the + Z axis is not pointing to the sun,while the position error of overlapping arcs is 0.6 km and the velocity error is 3 mm/s for the relay star when the + Z axis is pointing to the sun. This has important reference value for the long term operation of relay satellites.